Field of the Invention
The present invention relates to a sealing device for sealing a lead-through for a medical instrument, in particular for sealing the gap between a tube and a shaft of a medical instrument disposed in the tube during a micro-invasive procedure.
Description of the Background Art
An example of micro-invasive medical methods is laparoscopy. By means of a trocar, artificial access to the abdominal cavity of a patient is created through the abdominal wall. Through the lumen of a trocar tube remaining in the abdominal wall during laparoscopic surgery, an endoscope and/or other medical instruments (e.g. forceps, scissors, needle holders) may be introduced into the abdominal cavity. During laparoscopy, the abdomen is filled with carbon dioxide or another gas to create a pneumoperitoneum, a medical procedure-enabling cavity. Without special measures, this gas would escape through the tube. Therefore, numerous approaches were designed to occlude the lumen of the trocar tube as fluid-tight as possible, both when empty and when an instrument is inserted.
In part similar problems may arise in a working channel of an endoscope or when inserting a catheter into a blood vessel. In the latter case, however, not the escape of gas is to be prevented, but the escape of blood.
In U.S. Pat. No. 4,857,062, a valve for introducing a catheter into an artery is described. For sealing, a flexible element is provided, which is compressed to form a fluid-tight seal with a catheter.
In WO 93/01850 A1, a lever-operated seal for a tube is described. A wall made of an elastomer with an opening is stretched during insertion of an instrument into the tube through a plurality of levers, wherein the opening is increased.
In U.S. Pat. No. 5,366,446, an introducer assembly for use on the skin of a patient is described, which is designed for the insertion of tubes with different outside diameters. The assembly comprises a membrane made of a pierceable, elastomeric material in the center of a bellows.
EP 0 746 359 B1 describes a catheter check valve. For sealing, a rubber seal having an opening and a distal duckbill valve with a straight slot are provided.
In U.S. Pat. No. 4,430,081 a cannula is described for use with angiographic catheters. To seal against the entry of air or the leakage of blood from a blood vessel, a first seal having a slot, a second seal with a hole, and a third seal with a valve therein are provided, which are disposed adjacent to one another.
In WO 91/12838 A1, an infusion port is provided with several successively arranged resilient discs, each having circular openings or star-shaped slots which are arranged rotated against each other.
WO 98/32484 A1 describes a catheter introducer with a hemostasis valve. A sealing element comprises two perforated supporting discs, between which a sealing disc of soft-elastic foam plastic is provided with radially extending slots.
In U.S. Pat. No. 6,551,282 B1, a seal for sealing a tube when the shaft of an endoscope is inserted, is described. A wide annular seal is surrounded by a more rigid ring.
The sealing devices described each have specific advantages and disadvantages. A substantial and reliable sealing effect can be achieved easily with a sealing lip that presses with a very high contact pressure against the outer surface of the shaft of an instrument. However, this creates high sliding and static friction. A thin and/or soft sealing lip generates only very little sliding and static friction. However, it is not only less robust, it also has a reduced effect during lateral displacement of the shaft in the sealing device.
In all known thin and soft sealing lips, when you change the direction of movement of a shaft in the sealing device, a folding of the sealing lip is observed, which is accompanied by an appreciable change in the acting force between the shaft and the sealing device. This change in force can cause an involuntary movement of the shaft, or a movement that does not exactly correspond to the intentions of the medical staff, which can be bothersome or may even endanger the patient.